Kennehan Eric R, Munson Kyle T, Doucette Grayson S, Marshall Ashley R, Beard Matthew C, Asbury John B
Magnitude Instruments, State College, Pennsylvania 16803, United States.
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
J Phys Chem Lett. 2020 Mar 19;11(6):2291-2297. doi: 10.1021/acs.jpclett.0c00539. Epub 2020 Mar 6.
The ligand shell around colloidal quantum dots mediates the electron and energy transfer processes that underpin their use in optoelectronic and photocatalytic applications. Here, we show that the surface chemistry of carboxylate anchoring groups of oleate ligands passivating PbS quantum dots undergoes significant changes when the quantum dots are excited to their excitonic states. We directly probe the changes of surface chemistry using time-resolved mid-infrared spectroscopy that records the evolution of the vibrational frequencies of carboxylate groups following excitation of the electronic states. The data reveal a reduction of the Pb-O coordination of carboxylate anchoring groups to lead atoms at the quantum dot surfaces. The dynamic surface chemistry of the ligands may increase their surface mobility in the excited state and enhance the ability of molecular species to penetrate the ligand shell to undergo energy and charge transfer processes that depend sensitively on distance.
胶体量子点周围的配体壳层介导了电子和能量转移过程，这些过程是其在光电和光催化应用中得以应用的基础。在此，我们表明，当硫化铅量子点被激发到其激子态时，油酸配体中羧酸根锚定基团的表面化学性质会发生显著变化。我们使用时间分辨中红外光谱直接探测表面化学性质的变化，该光谱记录了电子态激发后羧酸根基团振动频率的演变。数据显示，羧酸根锚定基团与量子点表面铅原子的铅 - 氧配位减少。配体的动态表面化学性质可能会增加其在激发态下的表面迁移率，并增强分子物种穿透配体壳层以进行对距离敏感的能量和电荷转移过程的能力。
